The present invention relates to a system for binding a boot to a ski, intended for the practice of cross-country skiing.
Present-day ski boots for practicing cross-country skiing are being more and often more designed with means for laterally guiding and retaining the heel, which must allow a movememt of the foot which remains as much as possible in the longitudinal axis of the ski, thus ensuring better guidance of the ski itself. To this end, several types of construction for retaining the heel have been proposed.
One such construction consists of a longitudinal centering V recessed under the heel of the boot, in which a corresponding projecting V-section located on the ski is housed. The major drawback of this solution resides in the fact that centering of the boot on the ski is effected only in the final phase of the movement of the foot when it rests on the ski. Thus, this type of centering, which occurs only during the last ten millimeters of the movement, does not prevent the possibly off-centered and offset movements of the foot, particularly on hills. Moreover the desired centering may not take place at all due to torsional or other deformations, of the sole, as a result of which the V-notch may fail to engage the corresponding projecting section of the ski. At best, the skier is obliged to center his heel on the V of the ski himself. This voluntary attempt at centering then risks losses of balance, of speed, and therefore of time, which is prejudicial particularly in the case of competition.
Other types of construction employ hard tips, disposed in triangles and set up on the top surface of the ski and penetrating a zone of softer material located beneath the heel opposite said tips, when the foot reaches the final phase of its movement and when it rests on the ski. In this case, the same drawbacks are found as mentioned hereinabove, in addition to that of not having any centering at all, as the tips are planted in the soft part of the heel without being able to determine the path of movement of the boot as it comes to rest on the ski.
Finally, there is a device for guiding the boot on the ski, which acts during all the phases of movement of the foot. However, this device requires the assembly of a guide element which extends vertically with respect to the ski and of which the height is at least as great as the height of the lift of the foot when it moves. This device, which functions in principle, has the drawback of being unaesthetic on the one hand and relatively voluminous on the other hand. Moreover, it requires a guide device which is virtually as voluminous, adaptable to the boot itself and awkward for the user not only due to the weight of the assembly, but also due to its bulk, especially as far as the part adaptable to the boot is concerned, which prevents easy walking without the skis.